Femtocell Opinion, comment and reviews

IIR In-Building Summit Report – June 2010

Here are some highlights from this month’s IIR In-Building Summit held in London. I was only able to attend the first two days, but learnt a lot about the technical methods used to provide good in-building coverage today (mainly for very large buildings) and talked to several network planners about how the industry is changing the way they work.

Focus on larger buildings

The main theme of the event was how to efficiently (and cheaply) provide excellent coverage inside large commercial buildings – case studies for very large shopping malls, underground stations and even trains were given. The CTO of Zinwave, a leading supplier of active Distributed Antenna Systems (DAS), helpfully educated me on the scale of these solutions. For buildings up to about 25,000 square feet, passive DAS systems can be used. These “broadcast” the RF signals from basestations co-located inside the building through to antenna that are strategically placed to provide continuous coverage. Larger buildings require these RF signals to be amplified – hence the term Active DAS.

Often buildings will share the same RF distribution for all national mobile network providers, with the basestations being concentrated in a shared machine room. Companies such as Andrew (now part of CommScope) are a major player in providing all the “nuts and bolts” for radio transmission, were showing off a variety of hardware which included some pretty serious and high power RF combiners.

Futureproofing and the need to handle multiple bands/technologies

Putting this RF wiring into buildings can be expensive – a price range of $100,000K to $1M for projects for larger buildings was suggested, although smaller office blocks might be $10K to $20K. It also takes time – Paul-Flemming Hermann strongly advocated that all new buildings should have the wiring pre-installed just as you would for water or power, something I suspect is already happening in some countries. Chris Yates of Buro-Happold (the architects for several UK Olympic Stadiums and other international prestigious buildings) promoted the newly formed [Ed Note: and now defunct] Wireless Friendly Building Forum, setup to develop this concept further.

Such in-building systems aren’t restricted to carrying only 2G, 3G and even 4G mobile phone signals from all national networks. A speaker from London Metropolitan Police explained that “Blue-Light” services also need good coverage – large buildings in the US for example are required by law to provide 99% coverage for emergency services at all times. This means repeating signals from the European TETRA network or other whatever is used in each country. Even FM radio signals can be piped through the same RF distribution system.

This is where femtocells are at a disadvantage – they are tied to a single network operator, so you’d either need to deploy clusters of them (a stack of 4, one for each network), or restrict the excellent service they provide to a single network operator (quite feasible for business and residential purposes).

Operators being encouraged to collaborate more closely

O2 Ireland gave an example of the new stadium in Dublin. After many months (years) of unsuccessful meetings between the national network operators to decide on a common solution, the building owners gave them an ultimatum – either sort it out between yourselves or we’ll do it for you. The pace picked up somewhat and a joint design was agreed in a matter of weeks.

So what are the major pressures affecting network planners today?

I asked this question at one of the panel sessions, with all four panelists from different European countries resonating the same answers. There is a growing focus on getting operating costs down, specifically site rental and electrical power. This has led to greater co-operation with former competitors around site sharing as well as a close look at power management (e.g. can we turn off unused channels overnight).

Commercial pressure on site rental is changing

This continuing pressure to reduce operating costs is affecting the commercial dealings with large building providers. In the past, building owners might have charged high fees for the privilege of allowing mobile networks to install equipment and provide good coverage. Airports are probably one of the best examples – mobile network operators can make very profitable revenues if they capture incoming (business) vistors as they disembark, driving a need to provide excellent coverage both inbuilding and even onto the (parked) planes themselves. However, the fees being asked may have gone too far – I heard from one delegate that Orange no longer has any basestations onsite in BAA airports in the UK for cost reasons, instead “beaming” the signal in from nearby. This might work sufficiently for basic voice coverage, but must give their radio planning department headaches for any significant data traffic.

What we might see here is similar to the situation where householders want good indoor coverage but aren’t prepared to pay extra for it. We often see requests for free femtocells in areas of poor coverage - something that Asian operators such as KDDI and SoftBank are now offering. Large office/building owners may find they need to pay something towards good indoor coverage, or at least not expect to receive fees for providing access alone. Their customers will expect good indoor coverage and may measure the value of the building by this – some education might be needed to ensure poor service is not attributed to the network operator when the building owner is really at fault here.

Optimus Portugal report success with Enterprise Femtocells

This case study included several business customers where deployment of enterprise femtocells from Optimus Sinal On brand solved coverage problems in a variety of problems. Benefits included cost and speed of deployment – also customers liked seeing an attractive box that solved their problems. They demonstrated how they quickly resolved problems in a high rise office block and an old hospital building through clusters of enterprise femtocells, managed as a single supercell. For the technically minded, they allocate a separate UMTS carrier and between 2 and 5 scrambling codes. They found that cell reselection (i.e. when not actively in a call) worked excellently in both directions (entering/leaving 2G/3G), while handover worked when leaving or moving between femtocells. As with other femtocells today, handover of active calls when entering the area is not supported.

A variety of solutions other than just more cellsites.

Dean Bubley provided a summary of his latest short report on the different ways in which operators can deal with the data capacity crunch. He re-iterated Cooper’s Law, highlighting that LTE and other incremental improvements in RF transmission won’t deliver the 100x or more capacity increases required – physics come in to play. Large numbers of small cells offloading the traffic are the only way to deal with the predict traffic growth, especially for residential users. He believes every network operator has a different set of pain points and also discussed techniques including traffic shaping and compression to address these issues.

And one view of femtocells in this market

Steve Hartley from Ovum gave a good summary of the femtocell market status to date. Ovum haven’t really been too keen on femtocells in the past. They see them as a great coverage solution today, technically mature but still not completely “plug and play” – customer care calls remain at high levels for some early adopters.

He reported a survey showing that almost 40% of business owners are considering providing inbuilding voice service using femtocells within 2 years, compared with some 70% using DAS today. Surprisingly (for me) Voice over Wi-Fi was rated highly, with some 70% (up from 20% today) planning to use this method within 2 years.

Unfortunately I wasn’t able to attend this session, so don’t have the full background of the survey participants – surely businesses wouldn’t install such a wide variety of different systems at the same time?

Conclusion

I can see that for very large buildings with public access, such as shopping malls, sports stadiums etc, it makes sense to build in large Distributed Antenna Systems from the start. These should be future-proof to they can easily accommodate a variety of different services (FM Radio, Blue-Light emergency, mobile networks) and adapt to new technologies like LTE. These are expensive and time-consuming to install unless done during the early construction phase. Perhaps the new Wireless Friendly Building Forum will help drive a common approach here.

There are many existing buildings where the cost of putting in a new DAS system may be very expensive and/or time consuming – these are large projects. If CAT5 Ethernet cabling is already available (especially if it is unused), then plugging in femtocells on each floor could be a cheaper and simpler option – less skilled staff can be used to plan/install the system, and self-optimisation should reduce the ongoing operational/maintenance work.

One final comment was that as femtocell design capacity has grown from the original 4 active channels per device to some 32 or even 64, network planners haven’t yet fully appreciated the capacity and capability of the latest enterprise femtocells. A network planner suggested to me that these large femtocells could easily provide the capacity for a 10 storey office block on their own, connecting into the existing distributed antenna, and really become very interesting option in the future – perhaps not the topology originally envisaged by femtocell designers (who are thinking of lots of low cost units dotted around).